Process for preparing polysilane by catalytic dehydrogenative condensation of organosilane and metal complex catalyst therefor

ABSTRACT

A polysilane is produced by subjecting a trihydrosilane to hydrogenative condensation in the presence of a titanium or zirconim complex catalyst having a first group selected from a dialkylaminoalkylcyclopentadienyl group, an α-[(dialkylamino)alkyl]indenyl group and a β-[(dialkylamino)alkyl]indenyl group and a second group selected from a cyclopentadienyl group and a pentamethylcyclopentadienyl group. The above dialkylaminoalkyl group may be replaced by a branched alkyl group. The zirconium complexes are novel compounds.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims, under 35 USC 119, priority of JapaneseApplication Number 8-227988 filed Aug. 29, 1996.

BACKGROUND OF THE INVENTION

This invention relates to a process for preparing a polysilane bycatalytic dehydrogenative condensation of an organo-trihydrosilane inthe presence of an organotitanium or organozirconium complex catalyst.The present invention also pertains to a novel organozirconium complexcatalyst.

Polysilanes are useful for application as an electrically conductivematerial, a luminescent material, a photoelectric conversion material, anonlinear optical material, a photoresist material, a ceramic precursor,a polymerization initiator, etc.

One known process for the production of a polysilane includes subjectingan organo-trihydrosilane to dehydrogenative condensation in the presenceof a ziroconocene silyl complex such as Cp₂ZrMe₂ (Organometallics, vol.10, 3430-3432 (1991)). With this process, however, the weight averagemolecular weight of the polysilane is at most 5,000. To improve thepolymerization degree, a method has been proposed in which atri(perfluorophenyl)borane is added to the reaction system. Also knownis a method in which hydrogen gas produced in situ is continuouslyremoved from the reaction system. These methods, however, are notindustrially advantageous. Furthermore, even with the above methods, thedegree of polymerization is not high.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide aprocess which can produce a polysilane with a high degree ofpolymerization.

Another object of the present invention is to provide a zirconiumcomplex catalyst which is useful for the production of a polysilane.

In accomplishing the above objects, there is provided in accordance withthe present invention a zirconium complex represented by the followingformula:

wherein L¹ represents a first group selected from the group consistingof (a) a dialkylaminoalkylcyclopentadienyl or branchedalkylcyclopentadienyl group represented by the following formula (I):

wherein R¹ stands for an alkyl group having no more than 3 carbon atoms,X stands for N or CH and p represents an integer of 4 or less, (b) anα-[(dialkylamino)alkyl]indenyl or branched alkylindenyl grouprepresented by the following formula (II):

wherein R² stands for an alkyl group having no more than 3 carbon atoms,Y stands for N or CH and q represents an integer of 4 or less, and (c) aβ-[(dialkylamino)alkyl]indenyl or branched alkylindenyl grouprepresented by the following formula (III):

wherein R³ stands for an alkyl group having no more than 3 carbon atoms,Z stands for N or CH and m represents an integer of 4 or less, L²represents a second group selected from the group consisting of (d) acyclopentadienyl group represented by the formula (IV):

and (e) a pentamethylcyclopentadienyl group represented by the formula(V):

and L³ and L⁴ are each a monodendate anionic ligand.

In another aspect, the present invention provides a process for theproduction of a polysilane compound represented by the following formula(VII):

wherein R⁴ represents an alkyl group having no more than 12 carbonatoms, an aryl group having no more than 12 carbon atoms, a cycloalkylgroup having no more than 12 carbon atoms or an aralkyl group having nomore than 12 carbon atoms and n is an integer of at least 8, saidprocess comprising subjecting a trihydrosilane represented by thefollowing formula (VI):

R⁴SiH₃  (VI)

wherein R⁴ is as defined above, to dehydrogenative condensation in thepresence of a metal complex catalyst represented by the followingformula (VIII):

wherein M represents zirconium or titanium and L¹, L² L³ and L⁴ have thesame meaning as above.

Other objects, features and advantages of the present invention willbecome apparent from the detailed description of the preferredembodiments of the invention to follow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

In the process according to the present invention, anorganotrihydrosilane of the above formula (VI) is subjected to catalyticdehydrogenative condensation. In the formula (VI), the alkyl group R⁴may be, for example, phenyl, butyl, hexyl and β-phenylethyl.

The catalyst is a zirconium or titanium complex of the above formula(VIII). In the formula (I), R¹ is preferably methyl or ethyl and p ispreferably 2 or 3. In the formula (II), R² is preferably methyl or ethyland q is preferably 2 or 3. In the formula (III), R³ is preferablymethyl or ethyl and m is preferably 2 or 3. The catalyst is, used in acatalytically effective amount, generally 0.001 to 2 mol % based on theorganotrihydrosilane of the formula (VI).

Each of the ligands represented by the formulas (I)-(V) is acyclopentadienyl derivative. In the catalyst of the formula (VIII), L³and L⁴ are preferably independently selected from the group consistingof an alkyl group, an aryl group, an alkenyl group, an alkoxy group, anaralkyl group and a halogen group. If desired, a halogen-containingcatalyst, i.e. a catalyst of the formula (VIII) in which L³ and L⁴ arehalogen atoms, may be treated with a reducing agent, such astriethylaluminum, alumoxane, butyllithium or methyllithium, before orduring the hydrogenative condensation of the trihydrosilane.

The catalytic dehydrogenative condensation may be carried out with orwithout using a solvent. The solvent, when used, may be, for example, ahydrocarbon such as benzene, toluene or hexane, or an ether such asdiethyl ether, dibutyl ether or tetrahydrofuran. The reactiontemperature is generally 0-150° C., preferably from room temperature to100° C. Too high a temperature in excess of 150° C. may cause thedecomposition of the catalyst. A reaction temperature below 0° C.requires a long reaction time and is economically disadvantageous. It isadvisable to perform the reaction in an atmosphere of an inert gas suchas nitrogen, argon or methane. The polysilane may be separated from thereaction mixture by any known method such as florisil chromatography.

The following examples will further illustrate the present invention.

EXAMPLE 1 Preparation of[(N,N-Dimethylaminoethyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumDichloride

A tetrahydrofuran (THF) solution (8 ml) containing 527 mg (3.84 mmol) of(N,N-dimethylaminoethyl) cyclopentadiene was cooled to 0° C., to which 2ml of n-butyllithium were slowly added dropwise. The mixture was stirredfor 30 minutes at 0° C. and the stirring was further continued for 1hour at room temperature. The thus obtained THF solution containing acyclopentadiethyllitthium derivative was added dropwise through about 10minutes to a THF solution containing 1 g (3.01 mmol) ofpentamethylcyclopentadienylzirconium trichloride at room temperature andthe mixture was stirred overnight at room temperature. The solvent wasthen removed in vacuo and the residue was mixed with 20 ml of diethylether and filtered. The filtrate was mixed with 30 ml of pentane so thatlight yellow precipitates were formed. The precipitates were separatedby filtration and washed several times with pentane. The amount of theyellow crystalline powder was 760 mg (yield: 58.0%). The physicalproperties of the product are as follows:

¹H NMR (C₆D₆): δ 1.79 (15H, s), 2.10 (6H, s), 2.43 (2H, t, J=7.2 Hz),2.93 (2H, t, J=7.2 Hz), 5.63 (2H, t, J=2.6 Hz), 6.02 (2H, t, J=2.6 Hz);¹³C NMR (C₆D₆): δ 12.3 (q), 28.8 (t), 45.4 (q), 60.3 (t), 112.4 (d),111.7 (d), 123.8 (s), 133.8 (s); Elementary analysis; Calculated: C,52.63; H, 6.73; N, 3.23 for C₁₉H₂₉NCl₂Zr; Found: C, 52.35; H, 6.91; N,3.13.

EXAMPLE 2 Preparation of[(N,N-Dimethylaminopropyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumDichloride

Example 1 was repeated in the same manner as described except that(N,N-dimethylaminopropyl)cyclopentadiene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene. The yield was 55.0%. Thephysical properties of the product are as follows:

¹H NMR (C₆D₆): δ 1.80 (15H, s), 1.67-1.86 (2H, m), 2.07 (6H, s), 2.14(2H, t, J=7.5 Hz), 2.78 (2H, t, J=7.5 Hz), 5.66 (2H, t, J=2.6 Hz), 5.96(2H, t, J=2.6 Hz); ¹³C NMR (C₆D₆): δ 12.3 (q), 27.9 (t), 28.4 (t), 45.2(q), 59.0 (t), 112.7 (d), 117.0 (d), 123.8 (s), 135.4 (s); Elementaryanalysis; Calculated: C, 53.67; H, 6.98; N, 3.13 for C₂₀H₃₁NCl₂Zr;Found: C, 53.69; H, 7.28; N, 3.11.

EXAMPLE 3 Preparation of[(N,N-Dimethylaminoethyl)indenyl](pentamethylcyclopentadienyl)zirconiumDichloride

Example 1 was repeated in the same manner as described except that1(N,N-dimethylaminoindene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene. The yield was 33.0%. Thephysical properties of the product are as follows:

¹H NMR (C₆D₆): δ 1.80 (15H, s), 2.12 (6H, s), 2.36-2.44 (2H, m),2.93-2.96 (1H, m), 3.27-3.32 (1H, m), 5.63 (1H, d, J=2.9 Hz), 5.84 (1H,d, J=2.9 Hz), 7.06-7.25 (3H, m), 7.65 (1H, d, J=8.4 Hz); ¹³C NMR (C₆D₆):δ 12.4 (q), 27.3 (t), 45.5 (q), 57.8 (t), 96.8 (d), 113.9 (d), 115.5(d), 123.8 (s), 123.9 (d), 125.3 (s), 125.6 (d), 127.1 (d), 129.3 (s),131.2 (s).

EXAMPLE 4 Preparation of[1-(N,N-Dimethylaminopropyl)indenyl](pentamethylcyclopentadienyl)zirconiumDichloride

Example 1 was repeated in the same manner as described except that1(N,N-dimethylaminopropyl)indene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene. The yield was 33.0%. Thephysical properties of the product are as follows:

¹H NMR (C₆D₆): δ 1.81 (15H, s), 1.60-1.78 (2H, m), 2.68 (6H, s),2.04-2.13 (2H, m), 2.75-2.90 (1H, m), 3.15-3.30 (1H, m), 5.63 (1H, d,J=2.6 Hz), 5.77 (1H, d, J=2.6 Hz), 7.04-7.27 (3H, m), 7.68 (1H, d, J=8.3Hz); ¹³C NMR (C₆D₆): δ 12.4 (q), 26.2 (t), 28.5 (t), 45.3 (q), 59.0 (t),96.5 (d), 115.1 (d), 123.8 (s), 124.1 (d), 125.4 (d), 125.6 (d), 126.3(s), 127.1 (d), 129.4 (s), 131.4 (s).

EXAMPLE 5 Preparation of[1-(N,N-Dimethylaminoethyl)indenyl](cyclopentadienyl)zirconiumDichloride

Example 1 was repeated in the same manner as described except that1(N,N-dimethylaminoethyl)indene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene and thatcyclopentadienylzirconium trichloride was substituted forpentamethylcyclopentadienylzirconium trichloride. The yield was 35.0%.The physical properties of the product are as follows:

¹H NMR (C₆D₆): δ 2.10 (6H, s), 2.38-2.56 (2H, m), 3.06-3.19 (2H, s),5.77 (5H, s), 5.80 (1H, d, J=3.2 Hz), 6.61 (1H, d, J=3.2 Hz), 6.60-7.15(3H, m), 7.49 (1H, d, J=8.3 Hz); ¹³C NMR (C₆D₆): δ 26.4 (t), 45.4 (q),59.6 (t), 96.9 (d), 115.7 (s), 116.0 (d), 120.9 (s), 124.3 (d), 125.0(d), 125.1 (d), 125.5 (d), 125.7 (d), 126.9.

EXAMPLE 6 Preparation of[1-(N,N-Dimethylaminopropyl)indenyl](cyclopentadienyl)zirconiumDichloride

Example 1 was repeated in the same manner as described except that1(N,N-dimethylaminopropyl)indene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene and thatcyclopentadienylzirconium trichloride was substituted forpentamethylcyclopentadienylzirconium trichloride. The yield was 40.0%.The physical properties of the product are as follows:

¹H NMR (C₆D₆): δ 1.68-1.80 (2H, s), 2.07 (6H, s), 2.10-2.17 (2H, m),3.02-3.08 (2H, m), 5.75 (5H, s), 5.85 (1H, d, J=3.2 Hz), 6.47 (1H, d,J=3.2 Hz), 6.46-7.12 (3H, m), 7.51 (1H, d, J=8.2 Hz); ¹³C NMR (C₆D₆): δ25.7 (t), 28.3 (q), 45.4 (q), 59.0 (t), 97.4 (d), 115.7 (s) 116.1 (d),122.2 (s), 124.5 (d), 124.6 (d), 125.1 (d), 125.5 (d), 125.7 (d), 126.7(s).

EXAMPLE 7

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of [(N,N-dimethylaminoethyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconium dichloride (ascatalyst) and two equivalents (based on the catalyst) of n-butyllithiumwas reacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 10,700 on the basis of polystyrene.The ¹H NMR analysis of the reaction mixture revealed that the weightratio of the linear portion to the cyclic portion was 80:20. The ²⁹SiNMR analysis revealed that the linear polymer had a substantiallysyndiotactic structure.

COMPARATIVE EXAMPLE 1

Example 7 was repeated in the same manner as described except that(cyclopentadienyl)(pentamethylcyclopentadienyl)zirconium dichloride wassubstituted for[(N,N-dimethylaminoethyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumdichloride. The thus obtained polymer had a weight average molecularweight of 2,200 on the basis of polystyrene and a weight ratio of thelinear portion to the cyclic portion of 74:26. The polymer was found tohave an atactic structure and no regularity.

EXAMPLE 8

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.05mmol of [(N,N-dimethylaminoethyl))cyclopentadienyl](pentamethylcyclopentadienyl)zirconium dichloride (ascatalyst) and two equivalents (based on the catalyst) of n-butyllithiumwas reacted at 30° C. for 24 hours. The resulting reaction liquid wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 5,890 on the basis of polystyrene.The ¹H NMR analysis of the reaction mixture revealed that the weightratio of the linear portion to the cyclic portion was 80:20. The ²⁹SiNMR analysis revealed that the linear polymer had a substantiallysyndiotactic structure and the following physical properties.

¹H NMR (C₆D₆): δ 4.1-4.8 (1×0.8H), 4.8-5.1 (1×0.2H), 6.5-7.5 (5H).

EXAMPLE 9

A mixture containing 10.0 mmol of phenylsilane, 0.10 mmol of[(N,N-dimethylaminoethyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumdichloride (as catalyst) and two equivalents (based on the catalyst) ofn-butyllithium was reacted at 30° C. for 5 hours under a reducedpressure of 10 mmHg. The resulting reaction mixture was subjected to gelpermeation chromatography to obtain a polymer having a weight averagemolecular weight of 9,800 on the basis of polystyrene. The ¹H NMRanalysis of the reaction mixture revealed that the weight ratio of thelinear portion to the cyclic portion was 70:30. The ²⁹Si NMR analysisrevealed that the linear polymer had a substantially syndiotacticstructure.

EXAMPLE 10

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of [(N,N-dimethylaminopropyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconium dichloride (ascatalyst) and two equivalents (based on the catalyst) of n-butyllithiumwas reacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 10,700 on the basis of polystyrene.The ¹H NMR analysis of the reaction mixture revealed that the weightratio of the linear portion to the cyclic portion was 80:20. The ²⁹SiNMR analysis revealed that the linear polymer had a substantiallysyndiotactic structure.

EXAMPLE 11

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of [(N,N-dimethylaminopropyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconium dichloride (ascatalyst) and two equivalents (based on the catalyst) of n-butyllithiumwas reacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 10,400 on the basis of polystyrene.The ¹H NMR analysis of the reaction mixture revealed that the weightratio of the linear portion to the cyclic portion was 80:20. The ²⁹SiNMR analysis revealed that the linear polymer had a substantiallysyndiotactic structure.

EXAMPLE 12

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of[(N,N-dimethylaminopropyl)indenyl](pentamethylcyclopentadienyl)zirconiumdichloride (as catalyst) and two equivalents (based on the catalyst) ofn-butyllithium was reacted at 30° C. for one week. The resultingreaction mixture was subjected to gel permeation chromatography toobtain a polymer having a weight average molecular weight of 2,260 onthe basis of polystyrene. The ¹H NMR analysis of the reaction mixturerevealed that the weight ratio of the linear portion to the cyclicportion was 60:40. The ²⁹Si NMR analysis revealed that the linearpolymer had a substantially syndiotactic structure.

EXAMPLE 13

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene; 0.05mmol of1[(N,N-dimethylaminopropyl)indenyl](pentamethylcyclopentadienyl)zirconiumdichloride (as catalyst) and two equivalents (based on the catalyst) ofn-butyllithium was reacted at 30° C. for one week. The resultingreaction mixture was subjected to gel permeation chromatography toobtain a polymer having a weight average molecular weight of 2,900 onthe basis of polystyrene. The ¹H NMR analysis of the reaction mixturerevealed that the weight ratio of the linear portion to the cyclicportion was 52:48. The ²⁹Si NMR analysis revealed that the linearpolymer had a substantially syndiotactic structure.

EXAMPLE 14

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of [(N,N-dimethylaminoethyl)cyclopentadienyl](cyclopentadienyl)zirconium dichloride (as catalyst)and two equivalents (based on the catalyst) of n-butyllithium wasreacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 7,500 on the basis of polystyrene.The ¹H NMR analysis revealed that linear poly(phenylsilylene) wasformed. The ²⁹Si NMR analysis revealed that the linear polymer had asubstantially atactic structure.

EXAMPLE 15

A mixture containing 10.0 mmol of phenylsilane, 0.5 ml of toluene, 0.01mmol of [(N,N-dimethylaminopropyl)cyclopentadienyl](cyclopentadienyl)zirconium dichloride (as catalyst)and two equivalents (based on the catalyst) of n-butyllithium wasreacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 4,900 on the basis of polystyrene.The ¹H NMR analysis revealed that linear poly(phenylsilylene) wasformed. The ²⁹Si NMR analysis revealed that the linear polymer had asubstantially atactic structure.

EXAMPLE 16

A mixture containing 10.0 mmol of p-trifluoromethylphenylsilane, 0.5 mlof toluene, 0.01 mmol of[(N,N-dimethylaminoethyl)cyclopentadienyl](cyclopentadienyl)zirconiumdichloride (as catalyst) and two equivalents (based on the catalyst) ofn-butyllithium was reacted at 30° C. for one week. The resultingreaction mixture was subjected to gel permeation chromatography toobtain a polymer having a weight average molecular weight of 4,900 onthe basis of polystyrene. The ¹H NMR analysis revealed that linearpoly(phenylsilylene) was formed. The ²⁹Si NMR analysis revealed that thelinear polymer had a substantially atactic structure.

EXAMPLE 17

A mixture containing 10.0 mmol of n-butyllsilane, 0.5 ml of toluene,0.01 mmol of [(N,N-dimethylaminoethyl)cyclopentadienyl](cyclopentadienyl)zirconium dichloride (as catalyst)and two equivalents (based on the catalyst) of n-butyllithium wasreacted at 30° C. for one week. The resulting reaction mixture wassubjected to gel permeation chromatography to obtain a polymer having aweight average molecular weight of 696 on the basis of polystyrene.

EXAMPLE 18

Preparation of[(2-Methylpropyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumDichloride

Example 12 was repeated in the same manner as described except that(2methylpropyl)cyclopentadiene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene. The yield was 18.0%. Thephysical properties of the product are as follows:

¹H NMR (C₆D₆): δ 0.82 (6H, d, J=6.6 Hz), 1.66-1.73 (1H, m), 1.80 (15H,s), 2.63 (2H, d, J=7.0 Hz), 5.64 (2H, t, J=2.7 Hz), 5.92 (2H, t, J=2.7Hz); ¹³C NMR (C₆D₆): δ 3 12.3 (q), 22.5 (q), 30.5 (d), 39.9 (t), 112.5(d), 118.0.(d), 123.7 (s), 134.0 (s). Elementary analysis; Calculated:C, 54.52; H, 6.74 for C₁₉H₂₈Zr; Found: C, 54.65; H, 6.97.

EXAMPLE 19

Preparation of[(3-Methylbutyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumDichloride

Example 12 was repeated in the same manner as described except that(3-methylbutyl)cyclopentadiene was substituted for(N,N-dimethylaminoethyl)cyclopentadiene. The yield was 43.0%. Thephysical properties of the product are as follows:

¹H NMR (C₆D₆): δ 0.86 (6H, d, J=6.2 Hz), 1.40-1.50 (3H, m), 1.79 (15H,s), 2.76 (2H, t, J=7.8 Hz), 5.62 (2H, t, J=2.7 Hz), 5.93 (2H, t, J=2.7Hz); ¹³C NMR (C₆D₆): δ 6 12.3 (q), 22.6 (q), 38.0 (d), 28.4 (t), 40.0(t), 112.5 (d), 117.0 (d), 123.7 (s), 135.9 (s). Elementary analysis;Calculated: C, 55.53; H, 6.99 for C₂₀H₃₀Zr; Found: C, 54.96; H, 6.95.

EXAMPLE 20

A toluene solution (0.5 ml) containing 0.01 mmol of[(2methylpropyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumdichloride (as catalyst) was mixed with two equivalents (based on thecatalyst) of n-butyllithium at 78° C. The mixture was heated to 30° C.and then mixed with 10.0 mmol of phenylsilane. The resulting mixture wasreacted for one week under a nitrogen stream. The resulting reactionmixture was subjected to gel permeation chromatography to obtain apolymer having a weight average molecular weight of 9,040 on the basisof polystyrene. The ¹H NMR analysis of the reaction mixture revealedthat the weight ratio of the linear portion to the cyclic portion was79:21. The ²⁹Si NMR analysis revealed that the linear polymer had asubstantially syndiotactic structure.

EXAMPLE 21

A toluene solution (0.5 ml) containing 0.01 mmol of[(3methylbutyl)cyclopentadienyl](pentamethylcyclopentadienyl)zirconiumdichloride (as catalyst) was mixed with two equivalents (based on thecatalyst) of n-butyllithium at 78° C. The mixture was heated to 30° C.and then mixed with 10.0 mmol of phenylsilane. The resulting mixture wasreacted for one week under a nitrogen stream. The resulting reactionmixture was subjected to gel permeation chromatography to obtain apolymer having a weight average molecular weight of 8,960 on the basisof polystyrene. The ¹H NMR analysis of the reaction mixture revealedthat the weight ratio of the linear portion to the cyclic portion was70:30. The ²⁹Si NMR analysis revealed that the linear polymer had asubstantially syndiotactic structure.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all the changes which come within the meaning and rangeof equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A zirconium complex represented by the followingformula:

wherein L¹ represents a first group selected from the group consistingof: (a) a group represented by the following formula (I):

wherein R¹ stands for an alkyl group having no more than 3 carbon atoms,and p represents an integer of 2 or 3, (b) a group represented by thefollowing formula (II):

wherein R² stands for an alkyl group having no more than 3 carbon atoms,and q represents an integer of 2 or 3, and (c) a group represented bythe following formula (III):

wherein R³ stands for an alkyl group having no more than 3 carbon atoms,and m represents an integer of 1-4, L² represents a second groupselected from the group consisting of: (d) a cyclopentadienyl grouprepresented by the formula (IV):

and (e) a pentamethylcyclopentadienyl group represented by the formula(V):

and each of L³ and L⁴ is chlorine.
 2. A zirconium complex as claimed inclaim 1, wherein each of the alkyl groups R¹, R² and R³ is methyl orethyl and each of the integers p, q and m is 2 or 3.